U.S. patent application number 10/385011 was filed with the patent office on 2003-12-04 for security constrained transmission and load dispatch for electricity markets.
This patent application is currently assigned to SIEMENS POWER TRANSMISSION & DISTRIBUTION L.L.C.. Invention is credited to Peljto, Haso.
Application Number | 20030225676 10/385011 |
Document ID | / |
Family ID | 29586735 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030225676 |
Kind Code |
A1 |
Peljto, Haso |
December 4, 2003 |
Security constrained transmission and load dispatch for electricity
markets
Abstract
The present invention is an apparatus for optimizing security
constrained dispatch and pricing for the wholesale energy trading
market. The imbalance market uniquely requires a real-time market
for bidding and for providing the energy generation adjustments
required to satisfy the imbalance. The present invention address
the above noted needs by providing a real-time imbalance engine to
support and implement the equitable imbalance requirement via a
computer system implementation. Additionally, the present invention
allows the market generators and loads to provide electronic bids
for resolution while considering constraints on the demand and
supply system.
Inventors: |
Peljto, Haso; (Brooklyn
Park, MN) |
Correspondence
Address: |
Elsa Keller
Siemens Corporation
Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
SIEMENS POWER TRANSMISSION &
DISTRIBUTION L.L.C.
|
Family ID: |
29586735 |
Appl. No.: |
10/385011 |
Filed: |
March 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60363373 |
Mar 11, 2002 |
|
|
|
Current U.S.
Class: |
705/37 ; 705/1.1;
705/400; 705/412 |
Current CPC
Class: |
H02J 3/008 20130101;
G06Q 30/0283 20130101; Y04S 50/10 20130101; H02J 3/003 20200101;
G06Q 40/04 20130101; Y04S 10/50 20130101; Y04S 50/14 20130101; G06Q
50/06 20130101; Y04S 20/222 20130101; Y02B 70/3225 20130101 |
Class at
Publication: |
705/37 ; 705/1;
705/400; 705/412 |
International
Class: |
G06F 017/60 |
Claims
What is claimed is:
1. A computer implemented system for transmission and load optimal
market dispatch for clearance and pricing of energy in an energy
trading market spanning control areas of at least one market
participant, said system comprising: means for inputting
transmission security constraints of said at least one market
participant; means for clearing energy bids across said control
areas; means for optimizing the dispatch of energy considering said
transmission security constraints of said at least one market
participant; and means for pricing the dispatch of energy
considering said transmission security constraints.
2. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant energy limit.
3. The market dispatch system of claim 1, wherein said transmission
security constraint is the load energy limit.
4. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant regulation
availability.
5. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant regulation range.
6. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant spinning reserve
limit.
7. The market dispatch system of claim 1, wherein said transmission
security constraint is the load spinning reserve limit.
8. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant non-spinning reserve
limit.
9. The market dispatch system of claim 1, wherein said transmission
security constraint is the market participant capacity limit.
10. The market dispatch system of claim 1, wherein said
transmission security constraint is the load capacity limit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of U.S. Provisional Application No. 60/363,373 filed on Mar.
11, 2002 which is herein incorporated by reference.
TECHNICAL FIELD
[0002] This invention relates generally to the electronic
optimization management of wholesale electricity markets. In
particular, the invention pertains to the optimization of security
constrained dispatch resources for regional wholesale energy
markets.
BACKGROUND ART
[0003] This invention relates generally to a method of generating
the energy required to provide energy and ancillary services to
certain regions based on the availability of the generating
resources within Regional Transmission Organizations. In
particular, the invention pertains to generating and resolving
energy imbalance requirements for Regional Transmission
Organizations, Independent System Operators, and Independent
Transmission Providers.
[0004] A brief description of how the energy imbalance market
functions, as required by the Federal Energy Regulatory Commission
("FERC") regulations, may be helpful in understanding the field of
the present invention. In April 1996, FERC Order 888, "Promoting
Wholesale Competition Through Open Access Nondiscriminatory
Transmission Services by Public Utilities," required jurisdictional
public utilities to file open access transmission tariffs to allow
competition in the supply of wholesale electrical energy.. Under
the Order 888 market entities (utilities, merchant generators,
energy traders, etc) compete to provide energy based on several
factors including cost and availability of transfer capacity on
transmission facilities. Market entities can be limited from
providing energy to certain regions based on the availability of
transfer capacity on transmission facilities.
[0005] According to the framework established by Order 888,
provision of energy to resolve imbalances in the actual production
of energy versus scheduled energy was the responsibility of the
Transmission Provider and was covered as part of the Open Access
Tariff. The Transmission Provider usually satisfied this
requirement without a market mechanism by self-generating the
required energy and ancillary services.
[0006] In December 1999, FERC issued Order 2000, "Regional
Transmission Organizations." This order required jurisdictional
public utilities to form and participate in a Regional Transmission
Organization ("RTO"). The operational control of generators, and
transmission facilities was assigned to the Regional Transmission
Organization. Under FERC regulations, RTOs are required, among
other things, to ensure that its transmission customers have access
to an energy and ancillary services market. An RTO may cover parts
of one or more states within the United States. RTOs are required
to maintain efficient traffic grid management, to improve grid
reliability, to monitor and mitigate against opportunities for
discriminatory transmission practices, and to improve competition
in the wholesale electricity markets. The RTO is expected to
administer the open access transmission tariff, to exercise
operational control over, congestion management, reliability and to
plan the expansion of its transmission system. An additional set of
requirements for RTOs are that they remain independent of the
market participants.
[0007] In the framework of FERC Order 2000, the RTO is responsible
for providing transmission customers with access to an energy
market. Several market operators met the requirements of this order
by redispatching all energy in a real time market, followed by
financial settlement of energy imbalances. The requirements of this
order can also be met by the imbalance engine described below.
[0008] In July 2002, FERC issued a Notice of Proposed Rulemaking
(NOPR), "Remedying Undue Discrimination through Open Access
Transmission Service and Standard Electricity Market Design." This
NOPR announces FERC's intent to form a standard market design for
wholesale electrical energy. This NOPR requires public utilities to
place their transmission assets that are used in interstate
commerce under the control of an Independent Transmission Provider
or ITP. Among other functions, an ITP is responsible for operating
a day ahead market and a real time market for balancing energy.
[0009] In the day ahead market, spot market prices are generally
determined based on offers to supply energy and on forecast
requirements for load. A supply curve is determined using either
marginal costs or bid prices to rank order the plants beginning
with the cheapest plants. However, the FERC NOPR recognizes that to
create a truly competitive wholesale power market, the market must
also allow for price responsive loads.
[0010] In this framework, the market operator receives pricing
information from various wholesale market generators (typically
coal-fired power plants, hydroelectric power plants, nuclear power
plants, etc.) and receives energy requirements information from the
Load Serving Entities The market operator is then responsible for
determining an operating plan based on the offers provided by the
various market generators and the bids provided by the various Load
Serving Entities in the most cost effective manner.
[0011] Presently, all generators provide schedule information to
control area operators in the form of a statement of quantity of
energy they plan to generate and the time at which the energy will
be generated. The amount of energy may vary over the course of a
day, changing typically in hourly increments based on a variety of
factors. Under the framework of Order 2000 and the FERC NOPR,
market participants may voluntarily offer to supply additional
energy beyond the predetermined scheduled amount or alternatively
to reduced the energy supplied below the previously scheduled
amounts so that the RTO satisfy real time balancing requirements.
Additional energy costs arise when the market generator is
requested to meet a real-time and unanticipated shortage of energy.
Additionally, reduced energy costs may arise when the market
generator is requested to provide less energy than previously
contracted for in order to meet an unanticipated glut of
energy.
[0012] Computer systems within an RTO (Regional Transmission
Organization, Independent System Operator, or Independent
Transmission Provider) generate an daily operating plan that
determines for each time increment for the following day how much
energy will be supplied by each generator. The energy needs are
forecast for each day based on known statistical methods of
forecasting electrical demand. The forecast is typically accurate
but is seldom one hundred percent accurate as to the energy demands
for a certain region. Accordingly, as the energy plan from the
previous day is carried out by the RTO, the energy demands are not
one hundred percent accurate. More or less energy is actually
needed than that which was in the energy plan, and there may be
deficiencies in the amounts of energy actually supplied by
generators due to forced or unplanned outages for maintenance. This
variance in energy requirements is referred to as imbalance energy
or balancing energy requirements The RTO computer system addresses
that imbalance by using the bid and offer information received from
market participants.
[0013] The RTO is required by the FERC Order 2000 to implement an
energy imbalance market. The imbalance market requires a real-time
market for bidding to provide energy generation and load
adjustments to satisfy the imbalance. Therefore, instead of relying
on contracted prices generated one or more days in advance, a
method must be provided to allow market generators and loads to bid
for adjustments (for example, by providing more or less energy) in
a real-time manner during the day in real time as the energy
imbalance occurs.
[0014] However, additional optimization tools are necessary for
market clearing and commodity pricing based on security constrained
dispatch. The security constrained dispatch considers the overall
efficiency of the electricity markets subject to additional
requirements. The additional requirements include transmission
constraints and resource characteristics.
[0015] The imbalance market uniquely requires a real-time market
for bidding and for providing the energy generation adjustments
required to satisfy the imbalance. The present invention address
the above noted needs by providing a real-time imbalance engine to
support and implement the equitable imbalance requirement via a
computer system implementation. The imbalance engine enables the
RTO to operate a load following scheme to implement the FERC 2000
and NOPR requirements for implementation of an equitable energy
imbalance market. The imbalance market mechanism assures a means
other than the use of dedicated regulation and reserve resources or
bilateral contract markets to balance load and generation.
Additionally, the present invention allows the market generators
and loads to provide electronic bids for resolution by the
imbalance engine.
SUMMARY OF THE INVENTION
[0016] According to one aspect of the invention, there is provided
a computer implemented system for optimal market dispatch for
clearance and pricing of energy in an energy trading market
spanning control areas of at least one market participant, said
system comprising: means for inputting transmission security
constraints of said at least one market participant; means for
clearing energy bids across said control areas; means for
optimizing the dispatch of energy considering said transmission
security constraints of said at least one market participant; and
means for pricing the dispatch of energy considering said
transmission security constraints.
BRIEF DESCRIPTION OF THE FIGURES
[0017] The present invention will now be described with reference
to the accompanying drawings wherein:
[0018] FIG. 1 is a schematic diagram of the system in accordance
with the principles of the present invention.
DETAILED DESCRIPTION OF THE FIGURES
[0019] To illustrate the principles of the present invention, a
real-time imbalance engine and co-optimization engine as developed
by Siemens Power Transmission & Distribution, Inc., the
assignee of the present invention, shall be described in detail.
While this engine constitutes a preferred embodiment of the
invention, it is not the intention of applicants to limit the scope
of the invention to the particular details of this engine. Rather,
it is the intention of the applicants that the invention be defined
by the appended claims and all equivalents thereto.
[0020] Referring to FIG. 1, there is shown an exemplary block
diagram of the components and interfaces of an imbalance and
co-optimization engine 100 in accordance with the principles of the
present invention. The imbalance engine 100 consists generally of a
market user interface 102, an energy imbalance forecast engine 104,
a component for handling energy measurements processing, archiving
and accounting 106, a market optimal dispatch 108, a component for
balancing energy pricing 110, and a market database 114. A load
prediction engine 118 is alos included for predicting the load
demands on the energy dispatch system.
[0021] The real-time mechanism serve to assure means to balance the
load and generation of allowing for load following and other
ancillary services. Therefore, the performance is controlled in an
optimal manner at the same time as controlling network congestion
and transmission losses. The final result is that the real time
market co-optimization provides the efficiency of energy delivery
and the regulation capability and the reserve availability and
provides the key coordination for the control areas in an equitable
manner.
[0022] The real time market mechanism is designed as an
optimization tool for market clearance and commodity pricing based
on least cost security constrained dispatch. The market clearing
process presents the bid-based maximization of economic efficiency
of the overall wholesale electricity market subject to system
requirements, transmission constraints and resource management
characteristics. Co-optimization allows for the simultaneous
optimization, along with the real-time clearance and commodity
pricing, to take place with respect to multiple market commodities
such as balancing energy, regulation capacity, and spinning
reserve.
[0023] The optimization occurs across an internal hierarchical
order of components in the wholesale energy market: first the
control areas, then the reserve regions, generation zones, and
finally the load zones.
[0024] Other factors to be considered for co-optimization are
discussed below:
[0025] Network Losses
[0026] Energy network losses are considered using incremental loss
sensitivity factors. They present the influence of power injections
and withdrawals to network losses at each network node.
[0027] Transmission Congestion
[0028] Transmission congestion is relieved with minimal market
operational costs. Transmission constraints are specified using a
DC network model as incremental approximation around the base
point. Transmission line flows are limited in both directions,
Eventual network congestion differentiate locational marginal
prices in the way giving optimal market incentives from both an
operational and investment point of view.
[0029] Resource Constraints
[0030] Both resource capacity and inertia constraints are
considered as essential requirements for physical system
operations. Each resource can be considered a ramping constraint
over the considered time horizon.
[0031] Locational Marginal Pricing
[0032] Locational Marginal Pricing is the price based on marginal
operational costs for each market product. For regulation
capacities, locational marginal prices refer to the control area
locations, while for spinning reserve locational marginal prices,
reference is made back to the reserve region locations. Locational
marginal prices are calculated for each network node to support
pricing of both market participants and market non-participants.
These nodal balancing energy prices include network losses and
eventual transmission congestion.
[0033] It will be understood that other constraints on generation
and dispatch of energy may similarly be used in calculating the
optimal dispatch.
[0034] Market clearance and locational marginal pricing using
security constrained economic dispatch is described herein. The
objective is to balance load and generation and produce a bid-based
least-cost optimized dispatch for energy and ancillary services.
The constraints may include (1) system requirements for energy, (2)
control area requirements for regulation, (3) regional requirements
for reserve energy, (4) transmission line capacities, (5) network
losses, (6) ramp rate limits, (7) resource capacity limits. The
constraints are factored into producing an optimal dispatch which
provides for clearance, locational marginal pricing and network
congestion management.
[0035] The optimization objective can be characterized as the least
cost security constrained dispatch for energy and other ancillary
services. The optimization objective from a generator perspective
can be characterized as minimizing the total bid costs by
considering the benefits of energy consumption while discounting
the costs of energy generation, the costs of Up regulation, the
costs of down regulation, the costs of unit spinning reserve, and
the costs of load spinning reserve. Mathematically, the
constraining factors for total bid costs are characterized as
follows:
[0036] The benefits of energy consumption: 1 t T load L D En t ( E
n load t ) where D En t
[0037] is the operating cost function of the load energy
consumption at time interval t; and 2 E n load t
[0038] is the load energy consumption at time interval t
[0039] The costs of energy consumption can be characterized
mathematically as follows 3 t T unit G C En t ( E n unit t ) where
C En t
[0040] is the operating cost function of the unit energy generation
at time interval 4 E n unit t
[0041] is the unit energy generation at time interval t.
[0042] The costs of up regulation of energy is mathematically as
follows: 5 t T unit G C Reg Up ; t ( Reg unit Up ; t ) where C Reg
Up ; t
[0043] is the operating cost function of the up regulation costs at
time interval t; 6 Reg unit t
[0044] is the unit up regulation capacity at time interval t.
[0045] The costs of down regulation of energy is mathematically as
follows: 7 t T unit G C Reg Dn ; t ( Reg unit Dn ; t ) where C Reg
Dn ; t
[0046] is the operating cost function of the down regulation costs
at time interval t; 8 Reg unit t
[0047] is the unit down regulation capacity at time interval t.
[0048] The costs of unit spinning reserve is represented
mathematically as follows: 9 t T unit G C Res t ( Res unit t )
where C Res t
[0049] is the operating cost function of the spinning reserve costs
at time interval 10 Res unit t
[0050] is the unit spinning reserve at time interval t.
[0051] The costs of load spinning reserve are represented
mathematically as follows: 11 t T load L C Res t ( Res load t )
where C Res t
[0052] is the operating cost function of the spinning reserve costs
at time interval 12 Res load t
[0053] is the load spinning reserve at time interval t.
[0054] The optimization objective is to minimize the total costs of
these operating cost functions subject to the system requirements
for energy balance and control area regulation. These system
requirements are characterized as follows:
[0055] Energy balance must be optimized or maintained. 13 unite G
En unit t pf unit - load L En load t pf load = En native t t T
[0056] while the following control area regulation are maintained
at all times: 14 unite CA Reg unit Up ; t Reg CAreq Up ; t t T and
unite CA Reg unit Dn ; t Reg CAreq Dn ; t t T
[0057] The regulation reserve requirements must also be maintained:
15 unite RR Res unit t - load RR Res load t Res RRreq t t T
[0058] The DC transmission line constraints must additionally be
maintained. The transmission line constraints are represented by:
16 Pow line t = Pow line base + unite G SF line ; unit ( En unit t
- En unit base ) - load L SF line ; load ( En load t - En load base
) where Pow line base
[0059] is the line base flow
[0060] The total line flow limits must then be within a range of
line flow limits.
[0061] Another auxiliary constraint is the ramp rate constraints on
generation and load limits as defined by: 17 RR unit Dn En unit t -
En unit t - 1 RR unit Up unit G ; t T RR load Dn En load t - En
load t - 1 RR load Up load L ; t T
[0062] Additionally, there arc resource capacity constraints
imposed for security constrained dispatch. These constraints are
formulated below:
[0063] The unit energy limit is bounded in the following manner: 18
En unit t _ En unit t En unit t _ unit G ; t T
[0064] The load energy limit is bound in the following manner: 19
En load t _ En load t En load t _ load L ; t T
[0065] The unit regulation availability is bounded in the following
manner: 20 0 Reg unit Up ; t Reg unit Up ; t _ unit G ; t T and 0
Reg unit Dn ; t Reg unit Dn ; t _ unit G ; t T
[0066] The unit regulation range is bounded in the following
manner: 21 En unit t + Re g unit Up ; t Re g unit t _ unit G ; t T
and Re g unit t _ En unit t - Re g unit Dn ; t unit G ; t T
[0067] The unit spinning reserve limit is constrained in the
following manner: 22 0 Re s unit t Re s unit t _ unit G ; t T
[0068] The load spinning reserve limit is constrained in the
following manner: 23 0 Re s load t Re s load t _ load L ; t T
[0069] The unit capacity limits are constrained in the following
manner: 24 En unit t + Re g unit Up ; t + Re s unit t En unit _
unit G ; t T and En unit _ En unit t - Re g unit Dn ; t unit G ; t
T
[0070] The load capacity limit is constrained in the following
manner: 25 En load _ En load t - Re s load t load L ; t T
[0071] The imbalance market clearing process is based on non-linear
Dantzig-Wolfe decomposition supported by the revised simplex
method. Dantzig-Wolfe is a decomposition algorithm for linear
programming solutions. The decomposition of the market dispatch
problem results in the master problem related to overall imbalance
market optimization, and a set of sub-problems related to the
individual market participant optimizations.
[0072] To solve the master problem, the revised simplex method is
employed. The results provide optimal market clearing prices based
on sub-problem solutions found in previous iterations. These prices
are passed to the sub-problems as market coordination signals. The
new set of sub-problems are solved and the solutions are returned
back to the master problem. These responses are compared to the
market requirements for Inc and Dec energy and ancillary services
requirements. Any imbalance causes updates for market prices
leading to supply/demand balance for each market product.
[0073] Market participant optimization provides its best response
to posted market prices. These sub-problems present a multiple
product co-optimization from a single market participant's point of
view. The sub-problems absorb all economic and physical
characteristics specific to each market participant.
[0074] In accordance to the Dantzig-Wolfe approach, optimality must
be improved at each iteration. Otherwise, the optimal solution of
the market dispatch problem has been achieved. Tied bids will be
dispatched pro rata, i.e. proportionally to the length of tied bid
MW segments. The pro rata bids will be dispatched to the market
participant
[0075] The optimal results include both market clearing prices and
optimal balancing energy set points for each market participant.
The optimal results consist of the desired 5-minute average values
that are expected to be implemented in the future time. The
implementation of the imbalance market dispatch results will be
supported by standard ramping rules applied in accordance to market
participant dynamics. Ramping will start 1 minute before the start
of the operational 5-minute interval. This ramping rule will
provide balancing energy service as it is dispatched by the
imbalance market.
[0076] The above described embodiments are merely exemplary. Those
of ordinary skill in the art may readily devise their own
implementations that incorporate the principles of the present
invention and fall within the spirit and scope thereof.
* * * * *